1. Field of the Invention
The present invention relates to an image generating apparatus, and more particularly, it relates to an image generating apparatus comprising a push-up member for pushing up a paper and bringing the same into contact with a paper feed roller.
2. Description of the Background Art
In general, a feeder comprising a push-up member for pressing a paper against a paper feed roller carrying the same in a paper feed direction is known as that employed for an image generating apparatus such as a thermal transfer printer, as disclosed in Japanese Patent Laying-Open No. 8-175697 (1996), for example.
The feeder disclosed in the aforementioned Japanese Patent Laying-Open No. 8-175697 comprises a tray member loaded with papers, a paper position detecting mechanism detecting a paper feeding position (height), a cam (push-up member) for pushing up the tray member in response to the paper height, pivotal means (rotating shaft) on which the push-up member is rotatably mounted, a screw for rotationally driving the push-up member, a motor for rotating the screw, a nut for transmitting the rotation of the screw to the push-up member and a feed roll (paper feed roller). The feeder electrically detects the uppermost paper reaching the paper feeding position with the paper position detecting mechanism and electrically controls the motor, serving as a drive source for the cam (push-up member), to stop on the basis of a detection signal thereby changing the quantity of rotation of the cam (push-up member) so that the uppermost paper is on the paper feeding position in response to the number of the papers. In the feeder disclosed in the aforementioned Japanese Patent Laying-Open No. 8-175697, the screw driven by the motor rotates the push-up member (cam) about the pivotal means (rotating shaft) through the nut. This push-up member (cam) pushes up the tray member loaded with the papers from below, thereby pressing each paper against the feed roll (paper feed roller) and feeding the papers.
However, the feeder disclosed in the aforementioned Japanese Patent Laying-Open No. 8-175697 disadvantageously requires the electrical control, in order to rotate the cam (push-up member) for locating the uppermost paper on the paper feeding position in response to the number of the papers.
In order to solve this problem, there is proposed a feeder requiring no electrical control for changing the quantity of rotation of a push-up member in response to the number of papers, as disclosed in each of Japanese Patent Laying-Open Nos. 7-300244 (1995) and 9-194050 (1997).
The feeder proposed in the aforementioned Japanese Patent Laying-Open No. 7-300244 comprises a pressure plate (first push-up member) pushing up a hopper plate loaded with papers, a shaft on which the pressure plate is rotatably mounted, a rotatable pressure cam (second push-up member), a spring (spring member) having first and second ends mounted on the pressure cam and the pressure plate respectively and a paper feed roller. This feeder according to Japanese Patent Laying-Open No. 7-300244 rotates the pressure plate (first push-up member) about the shaft with urging force of the spring pulled through rotation of the pressure cam (second push-up member). Thus, the pressure plate (first push-up member) pushes up the hopper plate loaded with the papers from below and presses each paper against the paper feed roller, thereby feeding the papers. The feeder according to the aforementioned Japanese Patent Laying-Open No. 7-300244 automatically varies the quantity of rotation of the pressure plate with the number of the papers through expansion/contraction of the spring, to require no electrical control for changing the quantity of rotation of the pressure plate.
The feeder proposed in the aforementioned Japanese Patent Laying-Open No. 9-194050 comprises a pressure arm for pushing up a bottom plate loaded with papers, a rotatable support shaft supporting the pressure arm, a first lever rotatably mounted on the support shaft, a rotatable second lever, a spring (spring member) having first and second ends mounted on the first and second levers respectively and a paper feed roller. In this feeder disclosed in Japanese Patent Laying-Open No. 9-194050, it is conceivable that the pressure arm and the first lever constitute a first push-up member while the second lever constitutes a second push-up member. The second lever is so rotated as to rotate the first lever through the spring, thereby rotating the pressure arm about the support shaft. The rotated pressure arm pushes the bottom plate loaded with the papers from below and presses each paper against the paper feed roller, thereby feeding the papers. The feeder according to the aforementioned Japanese Patent Laying-Open No. 9-194050 automatically varies the quantity of rotation of the pressure arm with the number of the papers through expansion/contraction of the spring, to require no electrical control for changing the quantity of rotation of the pressure arm.
However, the feeder disclosed in the aforementioned Japanese Patent Laying-Open No. 7-300244 is provided with different rotating shafts for the pressure plate (first push-up member) and the pressure cam (second push-up member) respectively in the structure connecting the pressure plate (first push-up member) and the pressure cam (second push-up member) with each other through the spring member, and hence the number of components is disadvantageously increased.
The feeder disclosed in the aforementioned Japanese Patent Laying-Open No. 9-194050 is provided with the support shaft (rotating shaft) for the first lever and a rotating shaft for the second lever (second push-up member) respectively for individually rotating the first and second levers in the structure connecting the first lever constituting the first pushup member along with the pressure arm and the second lever constituting the second pushup member, and hence the number of components is disadvantageously increased. Further, the first push-up member is constituted of two members, i.e., the pressure arm and the first lever, to also increase the number of components.